博斯腾湖流域沉积物中多环芳烃的时空分布、来源及生态风险评价

在新疆博斯腾湖及其上游采集了8个表层沉积物和1根湖心沉积柱样品,分析了其中16种多环芳烃(PAHs)的含量,对其时空分布特征、来源和潜在生态风险进行了研究,并采用~(210)Pb同位素测年法分析了沉积速率和沉积柱的时间跨度.结果表明:表层沉积物样品中PAHs含量范围为57.37～360.24 ng·g~(-1)(干重),开都河沉积物中PAHs以低分子量PAHs(2～3环)为主,博斯腾湖沉积物中PAHs以高分子量PAHs(4～6环)为主.开都河和博斯腾湖沉积物中萘(Nap)、菲(Phe)、苯并(b)荧蒽(BbF)和茚并(1, 2, 3-cd)芘(IP)等单体的含量较高.空间分布呈现出上游河流开都河高于博斯腾湖区,且湖区污染主要集中在湖心处的污染特征.沉积柱样品中15种PAHs含量范围为29.85～211.13 ng·g~(-1),沉积速率为0.18 cm·a~(-1),PAHs组成以5环和6环为主.沉积时间跨度为1852—2016年,PAHs含量峰值出现在1994年.采用比值法对表层沉积物和沉积柱样品进行源解析表明,博斯腾湖流域PAHs主要来源于生物质和煤热解过程,近年来有向煤炭和石油燃烧复合源转变的倾向.效应区间低/中值法(ERL/ERM)和平均效应区间中值商法(M-ERM-Q)评估结果表明,博斯腾湖及其上游表层沉积物中PAHs表现出低生态风险.

Spatial and temporal distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments of the Bosten Lake watershed

In this study, 8 surface sediments and a sediment core were collected from Bosten Lake and its upstream in Xinjiang Province. The spatial distribution, source, and potential ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated. The ²¹⁰Pb isotope dating method was used to determine the deposition rate and the time span of the sediment core sample. The results show that the total concentrations of 16 PAHs ranged from 57.37 to 360.24 ng·g^-1(dry weight) in sediment. The low-molecular-weight PAHs (2 and 3 ring) were predominant in surface sediments of Kaidu River, however, the high-molecular-weight PAHs (4~6 ring) were predominant in surface sediment of Bosten Lake. Naphthalene, phenanthrene, benzo (b) fluoranthene and indeno (1,2,3-cd) pyrene were the major PAH individual compounds in surface sediments in both Kaidu River and Bosten Lake. The total PAHs concentrations in surface sediment in Kaidu river was higher than that in the Bosten Lake, and PAHs contamination in the lake area was mainly concentrated in the center of lake. The concentration of 15 PAHs in sediment core samples ranged from 29.85 to 211.13 ng·g^-1, and the deposition rate was 0.18 cm·a^-1. The 5 and 6 ring PAHs were the dominant congeners in the sediment core. The deposition time of sediment core were from 1852 to 2016, and the PAHs concentration reached a peak in 1994. Source apportionment based on diagnostic ratios indicated that the PAHs in sediment in Bosten Lake watershed were mainly from the low temperature pyrolysis process, such as the combustion of biomass and coal. In recent years, there was a tendency that PAHs were from the mixed sources based on coal and petroleum combustion. The ERL/ERM and M-ERM-Q values suggest that the PAHs in surface sediments in Bosten Lake watershed displayed lower ecological risk.